Photographic copying apparatus stripping mechanism and method



16, 1966 E. F. STIEVENART 3,266,797

PHOTOGRAPHIC COPYING APPARATUS STRIPPING MECHANISM AND METHOD Filed April 22, 1964 3 Sheets-Sheet 1 INVENTOR EMILE FRANS ST/EVENART BY WATSON, COLE,GR/NDLE & WATSON ATTORNEYS Aug. 16, 1966 E. F. STIEVENART PHOTOGRAPHIC COPYING APPARATUS STRIPPING MECHANISM AND METHOD Filed April 22, 1964 5 Sheets-Sheet 3 6, 1966 E. F. STIEVENART 3,266,797

PHOTOGRAPHIC COPYING APPARATUS STRIPPING MECHANISM AND METHOD Filed April 22, 1964 3 Sheets-Sheet 5 INVENTOR I EMILE FRANS ST/EVENART BY WATSON, COLE, GRINDLE & WATSON ATTORNEYS United States Patent 3,266 7'97 JPHUTOGRAPHIC CUPYHI IG APPARATUS STRIP- IPING MECHANISM AND METHOD Emile Frans Stievenart, Kiel-Antwerp, Belgium, assignor to Gevaert Photo-Producten N.V., Mortsel-Antwerp,

Belgium, a company of Beigium Filed Apr. 22, 1964, Ser. No. 361,728

10 Claims. (Cl. 27164) The present invention is a continuation-in-part of the United States patent application 310,826, filed Sept. 23, 1963.

The invention generally relates to document copying apparatus and more specifically to an improved copy sheet stripping mechanism for a photographic copying apparatus of the image-transfer type.

Photographic copying devices in which an exposed light-sensitive sheet, or a radiation-sensitive sheet generally, is urged in the presence of suitable processing liquid into intimate contact with an image-receiving sheet are well known in the art. Very little attention, however, has been given to the problem of separating from each other by means of mechanical instrument-alities the damp, tightly adhering sheets from each other.

One device which deals with sheet separation is disclosed in United States patent specifications 3,020,837 and 3,062,135 to C. R. Taylor et al. In this device, the receiving material is applied under pressure to the processed light-sensitive material with its leading edge extending over a separating knife at a point which is located immediately before the separating knife, and therefore only a very brief time is left for the diffusion transfer process to take place before the materials are separated. Moreover, complicated means have to be provided to permit displacement of the separating knife and a consequential extension of time for the diffusion transfer, in case a plurality of copies are to be reproduced.

Another device which performs the separation of sheets is disclosed in our pending United States patent application 310,926. The said device comprises a separating knife which is urged between the sheets, after said sheets have been completely pressed onto each other. By this system the problem of obtaining a sufficiently long contacting time of both adhering sheets is solved. The accurate mounting of the knife and the means for introducing it between the sheets without any risk of dam-aging the sheets may put, however, problems. In one of the embodiments disclosed in that application, the separating knife worked in conjunction with a presser bar which applied a rubbing force across the exposed face of the top sheet and flexed both sheets at a considerable angle. It has now been discovered that successful separation can be achieved by means of said presser bar alone and it is to this aspect of the earlier disclosure that the present application is directed.

The object of the invention is to provide a copying apparatus in which the separation of two adhering sheets is performed without a separating knife.

Another object of the invention is to provide a stripping mechanism which is simple of design and construction, and which has less need for careful adjustment than the mentioned devices.

Still another object of the invention is to provide a stripping mechanism that is of compact design so that it may be operatively associated with commercially avail able copying apparatus by the manufacturers of such apparatus, without considerable changes in the construction and design of the apparatus.

An advantage of an apparatus according to the presentinvention is that it is suited for the separation of a lightsensitive material and an image-receiving material not only when both are wetted. by the processing liquid prior to their being pressed together, but when just the lightsensitive material is wetted by the processing liquid, and

3,266,797 Patented August 16, 1966 even when the processing liquid necessary for accomplishing the diffusion transfer is only present between the contacting faces of both materials.

In both of the latter instances, only a small quantity of processing liquid is employed and both materials or sheets, consequently, strongly adhere to each other. They, therefore, have the important advantage that the produced copies are dry or almost so after separation.

The apparatus of the present invention is particularly suitable for association with photographic copying machines for producing copies according to the known silver halide diffusion transfer process.

According to this process a light-sensitive material comprising a silver halide emulsion layer is image-wise exposed to an original and pressed against an image-receiving material in the presence of processing liquid, a developing agent and a silver halide complexing agent, whereby the unexposed and undeveloped parts of the silver halide are complexed, and diffuse to the image-receiving material, where they are converted into a silver image by the action of developing nuclei. The basic disclosure of the diffusion transfer process appears in United States patent specification 2,352,014, filed July 21, 1941, by Rott and numerous improvements have now appeared in the patented art, to which reference may be had if desired for the details involved in the practice of this process.

In the preceding introduction to this specification, it has been stated that the invention relates to the separation of a radiation-sensitive sheet from an image-receiving sheet. It should be understood that in the present invention the term sheet envisions not only distinct individual sheets, but also web-like materials, which are cut into sheets prior to their separation. An example of such technique is found among others in the United Kingdom specification 852,838, filed Oct. 3, 1957, by Gevaert Photo-Producten N.V., in which an apparatus suitable for use in the production of images from exposed radiographic film by diffusion transfer has been disclosed.

Exemplary embodiments of the invention will be further explained by the following detailed description when read in conjunction with the accompanying drawings, in which:

FIG. 1 is a diagrammatic side elevation of a stripping mechanism embodying the principles of this invention, the parts thereof being seen in inoperative position;

FIG. 2 is a diagrammatic view of the mechanism of FIG. 1 with the parts in operative position;

FIG. 3 is a diagrammatic side view of a copying apparatus associated with a modified form of a separating mechanism according to th' invention, such mechanism being shown in inoperative position; and

FIG. 4 is a diagrammatic side view of the separating mechanism of the apparatus of FIG. 3, shown in the operative position.

The stripping mechanism shown in FIGS. 1 and 2 is intended to be used in association with any known copying apparatus of the type having a processing station for applying processing liquid to the image-wise exposed light-sensitive sheet, and a pressing station for pressing the moistened light-sensitive sheet against an image-receiving sheet so that the diffusion transfer can take place. Apparatus of this type are generally known in the art and therefore do not need to be described in detail in connection with the present stripping mechanism for separating the light-sensitive sheet and the imagereceiving sheet as delivered from the pressing station.

The stripping mechanism shown in FIGS. 1 and 2 comprises a roller 10 continuously driven by a motor (not shown), a freely rotatable roller 11 and a presser bar 12. The presser bar is pivotable around shaft 13. Freely rotatable roller 11 pivots bodily around the same shaft, and is arranged to be lifted by means of a hook- 19 shaped member 14, which depends from the lever 15 carrying the presser bar 12, and serves to engage a lever 16, which carries the roller 11, upon upward movement of lever 15.

Both rollers can have, for example, a diameter of mm., a length of 30 cm., and be made of stainless steel. The peripheral speed of roller 10 is equal to that of the outlet roller pair at the pressing station of the proceeding copying apparatus. The presser bar 12 as well as the lever 15 are preferably made out of a rod of stainless steel with a diameter of 3.5 mm., and said presser bar extends over the full length of roller 10 parallel to said roller.

A compression spring 17 is provided between the levers 15 and 16, which urges lever 16 against the hook member 14, and a solenoid 18 which controls the movement of the lever 15, in conjunction with a tension spring 27. Other parts will be mentioned during the course of the description of this operation.

The operation of the mechanism is as follows.

An image-receiving sheet 19 and a light-sensitive sheet 20, both adhering to each other on departure from the copying apparatus, are advanced towards the stripping mechanism over a support 21. The light-sensitive sheet lies below and leads the other by a short distance, say, varying between about one third and one-half inch. At the moment the sheets reach the position as shown in FIG. 1, the leading edge of sheet 20 actuates the lever of a microswitch 22. Said lever is in the nature of a leaf spring which is biased to overcome the switch button bias when a sheet is absent thereat. The leading edge of the sheet 20 lifts the lever of the microswitch whereby the electrical circuit of the solenoid 18 for lowering the lever 15 is closed. The lever 15 first passes through a position situated between those shown in FIGS. 1 and 2. In such position, freely rotatable roller 11 will contact the leading margin of sheet 20 and press it against the periphery of the driven roller 10 so that it will be positively advanced by the rollers in the direction of the broken lines 23 (FIG. 2).

Continued lowering of lever 15, thereafter, has the following effect. The member 14 releases the lever 16, so that the roller 11 remains resting, biased by the spring 17, on the roller 10, and the presser bar 12 will approach the periphery of roller 10, so as to finally take a position as shown in FIG. 2. Two actions now cooperate for separating the receiving sheet 19 from the light-sensitive sheet 20.

First, there is the sharp deflection of the sheets around the periphery of roller 10, so that the inherent tendency of any sheet material to resist deflection, will cause the sheet 19, which is pressed at only one point against the roller 10, to tend to separate from the sheet 20 which is forceably curved over 90 around the roller 10.

Second, there is the rubbing action of the presser bar 12 on the back side of the sheet 19 which makes the said sheet curl towards the side to which friction is applied.

Upon continuous further advance of the sheets by the rollers 10 and 11, the sheet 19 continues to diverge from the sheet 20, and passes between guide plates 24 so as to follow a path 25 also indicated in broken lines in FIG. 2. The sheet 20, on the other hand leaves the mechanism between the guide plates 26.

The lever of the microswitch 22 which was actuated by the leading margin of sheet 20, remains lifted so long as the sheet 20 passes therebeneath between guide plates 26. When the trailing edge of the said sheet has cleared the lever of the microswitch, the lever returns to its initial position, and the circuit of the solenoid 18 is de-energized, so that the stripping mechanism by the action of the spring 27, restrained at its opposite end to a fixed position on the frame or the like indicated diagrammatically, is returned to its initial position as shown in FIG. 1.

The removal of the separated sheets between the guide plates 24, 26 may be completed by hand, or by one or more additional driven roller pairs arranged to advance said sheets between the respective guide plates.

It should be noted that the just-described embodiment is not limited to all details which have been dealt with hereinbefore, and that various changes are possible which do not change the principle of the invention.

For example, the microswitch 22 may be replaced by another electrical sensing device, e.g. a photoelectric cell, for controlling the solenoid 18.

The roller 10 may be driven by the mechanism of the copying apparatus itself. In this way the synchronisation of the roller 10, driven by a separate motor as described for the present embodiment, presents even less problems.

In another embodiment the roller 10 may have normally an inoperative position, and only start turning when the solenoid is energized, etc.

The rollers may be made out :of other materials than stainless steel. They may consist of copper, aluminum, etc., with a smooth or roughened surface, as desired.

They may also have a resilient covering, permitting the presser bar 12 to slightly impress the roller surface so as to increase even further the curvature of sheet 20.

Also the presser bar 12 may be made out of other materials than stainless steel. This bar may further be covered with a hose made of a material having a relative great friction coefiicient, such as rubber or plastic. In any case the rubbing force should be applied substantially uniformly across the width of the sheet.

Occasionally, a fixed blade may be provided running parallel to but spaced from roller 10, as shown in dotted lines at 29 representing the side edge of such blade.

Such blade may be useful in directing sheet 19 between the guide plates 24 after it has been diverged from the sheet 20 by the pressure bar 12.

Another embodiment of the invention is shown in FIGS. 3 and 4. In these figures there is shown a copying apparatus in association with a separating mechanism.

The copying apparatus 30 which comprises a developing station 31 with a lick-roller applicator system for applying the processing liquid to the emulsion side of the lightsensitive material, a squeegee station 32 for removing the excessive processing liquid from the light-sensitive material, and a pressing station 33 for pressing the moistened light-sensitive sheet against the dry image-receiving sheet, has been described in our pending United States patent application 310,826 to which reference may be had for all details.

The exposed light-sensitive sheet follows a path indicated by the dashed line 34 through the copying apparatus 30, whereas the image-receiving sheet follows a path similarly indicated at 35.

When leaving the copying apparatus, both sheets are intimately pressed together, and the diffusion transfer process takes place during the travel of the sheets between the guides 36 up to the separating mechanism. For sake of clarity, the path of both sheets between said guide plates is represented by only one broken line.

The separating mechanism comprises the guide plates 37 and 38, made, for instance, of hard polyvinylchloride or like plastic material, which are both jointly pivotable around shaft 39, and the driven pressure rollers 40 and 41, made out of stainless steel.

As is revealed in FIG. 4, the upper guide plate 37 projects forwardly of the lower guide plate 38, so as to press, when in operative position, its rounded front edge 42 against the periphery of roller 41. Further are provided an electrical sensing device 43, indicated diagrammatically, a solenoid 44 for shifting the guide plate array 37, 38 between its two positions, and a driven roller 45 for advancing the sheets.

The operation of the modified form of separating device is as follows.

When both sheets have passed the guide plates 36, they are further advanced along the path indicated by the broken line by the driven roller 45 which resiliently contacts the end of the lower guide plate 38, which together with plate 37 is in inoperative position shown in FIG. 3.

When the leading edge of the light-sensitive sheet, which, as in the earlier embodiment, is leading that of the image-receiving sheet over a distance of about one third to one half inch, arrives between the nip of the driven pressure rollers 40, 41, it actuates the sensing device 43 whereby the solenoid 44 is energized.

The guide plates 37 and 355 are thereby swung down into the operative position in which the front edge 42 of the plate 37 presses against the roller 41. The light-sensitive sheet is curved around the roller 4-1 over about 45, whereas the leading edge of the image-receiving sheet, which was slightly trailing in respect of that of the lightsensitive sheet and as a consequence thereof was not gripped between the pressure rollers 40 and 411, curls upwardly owing to the strong rubbing of the front edge 42 of the plate 37 over the back side of said sheet. Upon further turning of the rollers 40 and 41, the light-sensitive sheet is removed over the path 34, whereas the image-receiving sheet moves upwardly over the path 35 where it passes between the guide plates 47, and is finally driven out by the rollers 48 and 49. After the sheet has left the separating mechanism, the sensing device 43 returns to its initial position, thereby de-energizing the solenoid 44- so that by means of spring means (not shown) the guide plates are returned to their inoperative position.

From the FIGURES 3 and 4 it will be seen that the driving action of the roller 45 stops when the lower guide plate 38 moves to its operative position and thus away from the said roller. The advancing of the sheets, however, is not affected since by that time the lower sheet is positively gripped between the rollers 40 and 41.

It is clear that this particular arrangement of the roller 45 is not essential for the operation of the device, and other means may be employed for advancing of the sheets up to the rollers 40, 41.

Moreover, alterations can be made in the modified embodiment. For example, the front edge 42 of the guide plate 37 may have another shape than its present rounded form, provided such other shape is conductive to the rubbing action to be performed by that edge. The roller 41 may be made out of, or covered with, a resilient material, the guide plates may only partially pivot so as to let only a front section perform a movement for urging the sheets against the roller 41, the lower guide plate 38 may even remain stationary and only the upper guide plate may move so as to approach the lower guide plate until it contacts the roller 41, to mention a few possibilities.

I claim:

1. In a copying apparatus wherein image-transferring sheet material is intimately contacted by sheet-pressing means with an image-receiving sheet material and subsequently separated therefrom, a mechanism for separating sheets delivered thereto with the leading edge of one material projecting slightly forwardly of the leading edge of the other material, comprising material advancing means for positively gripping the leading margin of said one material at a fixed locus, means operable to exert a rubbing action generally uniformly across the exposed face of the other material just in advance of said fixed locus and prior to any engagement of said other material by said advancing means, whereby a tendency to curl and to become separated from said one material is imparted to said other material, and guide means for receiving at least said other material after the leading edge thereof has become separated from said one material and for directing the same along a path diverging from the direction of said advance of said other material.

2. In a copying apparatus wherein image-transferring sheet material is intimately contacted by sheet-pressing means with an image-receiving sheet material and subse 6 quently separated therefrom, a mechanism for separating sheets delivered thereto with the leading edge of one material projecting slightly forwardly of the leading edge of the other material, comprising a driven pair of feed rollers for positively gripping the leading margin for said one material; a presser member movable into engagement with the exposed face of said other material substantially uniformly thereacross prior to said other material being gripped by said rollers, said member frictionally contacting said material adjacent the periphery of said feed rollers at a point spaced from the nip thereof and flexing the same through a sharp angle, whereby said other material is caused to separate from said one material; and a guide for diverting the other material as the same separates from said one material.

3. An apparatus as in claim 2 including means for sensing the entry of the leading edge of said one material into said feed rollers and for operating the presser member in response thereto.

4. An apparatus as in claim 2 wherein said presser member is a substantially rigid rod extending generally parallel to the axes of said feed rollers.

5. An apparatus as in claim 2 wherein said presser member is the termination of a guide element.

6. A method of separating two adhering sheets of sheet material which comprises the steps of feeding said ad-' hering sheets lengthwise into a separating zone; positively constraining one of said sheets passing through said zone into an arcuate path of small radius relative to the sheet length, while leaving the other of said sheets unrestrained at least adjacent its leading end; applying to the other of said sheets across its width at a point on said arcuate path sliding frictional resistance to the lengthwise motion thereof, whereby said other sheet is caused to curl and separate from the first sheet; and removing the sheets from said separating zone along separate paths.

7. The method of claim 6 wherein said frictional resistance is applied adjacent the upstream end of said path and serves likewise to supply the constraining force to said first sheet at such end of said path.

8. The method of claim 7 wherein said sheets are fed to said zone with the leading edge of said first sheet projecting slightly forwardly and said projecting edge is engaged to supply the constraining force to said sheet at the downstream end of said path.

9. Apparatus for separating two adhering sheets of sheet material comprising means for engaging and positively advancing one of such sheets, the other of said sheets being free of such engagement and advancing only by reason of its adhering relation to said first sheet, an arcuate surface beneath said first sheet for supporting said sheets while advancing, and a friction member arranged on the opposite side of said sheets fromsaid surface and extending across the width of said other sheet, said member being engageable with said other sheet while the same receives support from said surface to apply sliding frictional resistance thereto, whereby said other sheet is caused to curl and separate from said first sheet; and guide means for removing said sheets from said surface along separate paths.

1.0. The apparatus of claim 9 wherein said arcuate surface is a portion of the periphery of one of a pair of feed rolls which engage and advance said first sheet.

References Cited by the Examiner UNITED STATES PATENTS 2,754,994 7/1956 Cole 156584 X 2,765,205 10/1956 Capella et a1 l56-584 X 2,804,304 8/1957 Taini 271-64 2,822,170 2/1958 Frantz 27l-64 ROBERT B. REEVES, Primary Examiner. M. HENSON WOOD, ]R., Examiner.

Assistant Examiners. 

6. A METHOD OF SEPARATING TWO ADHERING SHEETS OF SHEET MATERIAL WHICH COMPRISES THE STEPS OF FEEDING SAID ADHERING SHEETS LENGTHWISE INTO A SEPARATING ZONE; POSITIVELY CONSTRAINING ONE OF SAID SHEETS PASSING THROUGH SAID ZONE INTO AN ACRUATE PATH OF SMALL RADIUS RELATIVE TO THE SHEET LENGTH, WHILE LEAVING THE OTHER OF SAID SHEETS UNRESTRAINED AT LEAST ADJACENT ITS LEADING END; APPLYING TO THE OTHER OF SAID SHEETS ACROSS ITS WIDTH AT A POINT ON SAID ARCUATE PATH SLIDING FRICTIONAL RESISTANCE TO THE LENGTHWISE MOTON THEREOF, WHEREBY SAD OTHER SHEET IS CAUSED TO CURL AND SEPARATE FROM THE FIRST SHEET; AND REMOVING THE SHEETS FROM SAID SEPARATING ZONE ALONG SEPARATGE PATHS. 